What to do when you are “stuck” on the RV Sonne in the central Pacific for 2 months?

Well, you can do a lot of bird and marine mammal watching. You can work out in the gym or even relax in the spacious on-board sauna. You could also rediscover your love for knitting and embroidery. Those are just some of the options. But if you are me, you are here to do some science! And that means worms!

nodule and nematode, Copyright Lara Macheriotou

Not just any kind of regular backyard earth-worm, but microscopically small worms from the abyss more than 3 km below the sea surface. How does one get these worms then? You send this funky lunar-lander-looking apparatus (aka multi-corer) down to the seafloor which holds 12 plastic open cylinders. These are then pushed into the soft bottom, they close on either side and collect a 60cm-long sediment core. And that’s where you will find the worms, or more scientifically, the nematodes. Since they are so small I need to extract them from the sediment in order to study them and this is achieved through a centrifugation step which separates the sediment from the much lighter nematodes.

My personal mission (or PhD as they call it) is to figure out which species are in the area, why, and how their populations are connected. To this end I will identify them using morphological characteristics and molecular methods, i.e. sequencing species-specific DNA fragments. I will try to relate the presence or absence of species to different environmental characteristics such as Total Organic Carbon content (TOC), sediment grain size or habitat geomorphology. Finally, I will try to uncover if areas that are separated by 10’s of km’s share the same species, and whether these are exchanging genetic material, i.e. interbreeding with one another. This area, the Clarion-Clipperton Fracture Zone is mostly undescribed biologically and so these analyses will provide new information concerning the character of deep-sea ecosystems.